US20130098551A1 - Electron beam plasma source with arrayed plasma sources for uniform plasma generation - Google Patents
Electron beam plasma source with arrayed plasma sources for uniform plasma generation Download PDFInfo
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- US20130098551A1 US20130098551A1 US13/595,201 US201213595201A US2013098551A1 US 20130098551 A1 US20130098551 A1 US 20130098551A1 US 201213595201 A US201213595201 A US 201213595201A US 2013098551 A1 US2013098551 A1 US 2013098551A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32321—Discharge generated by other radiation
- H01J37/3233—Discharge generated by other radiation using charged particles
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
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- a plasma reactor for processing a workpiece can employ an electron beam as a plasma source.
- Such a plasma reactor can exhibit non-uniform distribution of processing results (e.g., distribution of etch rate across the surface of a workpiece) due to non-uniform distribution of electron density and/or kinetic energy within the electron beam.
- processing results e.g., distribution of etch rate across the surface of a workpiece
- Such non-uniformities can be distributed along the direction of beam propagation and can also be distributed in a direction transverse to the beam propagation direction.
- a plasma reactor for processing a workpiece includes a workpiece processing chamber having a processing chamber enclosure comprising a ceiling and a side wall and an electron beam opening in said side wall, a workpiece support pedestal in said processing chamber having a work lace support surface facing said ceiling and defining a workpiece processing region between said workpiece support surface and said ceiling, said electron beam opening facing said workpiece processing region.
- the plasma reactor further comprises an electron beam source chamber comprising an electron beam source chamber enclosure that is open to said electron beam opening of said workpiece processing chamber, and an array of plasma sources distributed along a portion of said electron beam source chamber enclosure opposite from said electron beam opening, each of said plasma sources comprising a supply of plasma source power and a plasma source power applicator coupled to the supply of plasma source power.
- a controller governs each supply of plasma source power of each of said plasma sources.
- the array of plasma sources is distributed along direction parallel with a plane of said workpiece support surface.
- the plasma sources affect plasma electron density in respective portions of said electron beam source chamber, said respective portions distributed along a direction parallel with a plane of said workpiece support surface.
- FIGS. 1A and 1B are top and side views, respectively, of a plasma reactor employing an electron beam to produce a plasma in a workpiece processing chamber, and of the electron beam source including an array of toroidal plasma sources, in accordance with a first embodiment.
- FIG. 1C is an enlarged view of a portion of FIG. 1B .
- FIG. 1D is a cross-sectional view taken along lines 1 D- 1 D of FIG. 1C .
- FIGS. 2A , 2 B and 2 C are side, top and end views, respectively, of a plasma reactor employing an electron beam to produce a plasma in a workpiece processing chamber, and of the electron beam source including an array of capacitively coupled plasma sources, in accordance with a second embodiment.
- FIGS. 3A and 3B are side and end views, respectively, of a plasma reactor employing an electron beam to produce a plasma in a workpiece processing chamber, and of the electron beam source including an array of inductively coupled plasma sources, in accordance with a third embodiment.
- FIG. 4 is a top view of a plasma reactor employing an electron beam to produce a plasma is a workpiece processing chamber, and of the electron beam source including an array of separate electron beam source chambers, in accordance with a fourth embodiment.
- FIGS. 1A and 1F are top and side views, respectively, of a plasma reactor having an electron beam plasma source employing a configurable array of plasma sources affecting uniformity of an electron beam, in accordance with a first embodiment.
- the reactor includes a process chamber 100 enclosed by a cylindrical side wall 102 , a floor 104 and a ceiling 106 .
- a workpiece support pedestal 108 supports a workpiece 110 , such as a semiconductor wafer, the pedestal. 108 being movable in the axial (e.g., vertical) direction.
- a gas distribution plate 112 is integrated with or mounted on the ceiling 106 , and receives process gas from a process gas supply 114 .
- a vacuum pump 116 evacuates the chamber through the floor 104 .
- a process region 118 is defined between the workpiece 110 and the gas distribution plate 112 . Within the process region 118 , the process gas is ionized to produce a plasma for processing of the workpiece 110 .
- the plasma is generated in the process region 118 of the process chamber 100 by an electron beam from an electron beam source 120 .
- the electron beam source 120 includes a plasma generation chamber 122 outside of the process chamber 100 and having a conductive enclosure 124 .
- the conductive enclosure 124 has a gas inlet or neck. 125 .
- An electron beam source gas supply 127 is coupled to the gas inlet 125 .
- the conductive enclosure 124 has an opening 124 a facing the process region 118 through an opening 102 a in the sidewall 102 of the process chamber 100 through which the electron beam enters the process chamber 100 .
- the electron beam source 120 includes an extraction grid 126 between the opening 124 a and the plasma generation chamber 122 , and an acceleration grid 128 between the extraction grid 126 and the process region 118 , best seen in the enlarged view of FIG. 1C .
- the extraction grid 126 and the acceleration grid 128 may be formed as separate conductive meshes, for example.
- the extraction grid 126 and the acceleration grid 128 are mounted with insulators 130 , 132 , respectively, so as to be electrically insulated from one another and from the conductive enclosure 124 . However, the acceleration grid 128 is in electrical contact with the side wall 102 of the chamber 100 .
- the openings 124 a and 102 a and the extraction and acceleration grids 126 , 128 are mutually congruent, generally, and define a thin wide flow path for an electron beam into the processing region 118 .
- the width of the flow path is about the diameter of the workpiece 110 (e.g., 100-500 mm), while the height of the flow path is less than about two inches.
- the electron beam source 120 further includes a pair of electromagnets 134 - 1 and 134 - 2 aligned with the electron beam source 120 , and producing a magnetic field parallel to the direction of the electron beam.
- the electron beam flows across the processing region 118 over the workplece 110 , and is absorbed on the opposite side of the processing region 118 by a beam dump 136 .
- the beam dump 136 is a conductive body having a shape adapted to capture the wide thin electron beam.
- a negative terminal of plasma D.C. discharge voltage supply 140 is coupled to the conductive enclosure 124 , whereas a positive terminal of the voltage supply 140 is connected to the extraction grid 126 .
- a negative terminal of an electron beam acceleration voltage supply 142 is connected to the extraction grid 126 , and positive terminal is connected to the grounded sidewall 102 of the process chamber 100 .
- the electrons extracted from the DC discharge plasma through the extraction grid 126 are accelerated as they travel towards the acceleration grid 128 by the potential difference (typically of the order of a few kV) provided by the voltage supply 142 .
- the negative terminal of voltage supply 142 may be coupled to the conductive enclosure 124 , instead of the extraction grid 126 .
- the voltage supply 142 not only performs work to accelerate the electrons, but also to sustain DC discharge.
- the voltage supply 140 in this case, only performs work on a small portion of a discharge current caused by electrons that do not make it through the openings and bombard the extraction grid.
- a coil current supply 146 is coupled to the electromagnets 134 - 1 and 134 - 2 .
- Plasma is generated within the chamber 122 of the electron beam source 120 by a D.C. gas discharge produced by power from the voltage supply 140 , which provides a voltage typically of the order of a few hundred volts. This D.C. gas discharge is the main plasma source of the electron beam source 120 .
- Electrons are extracted from the plasma in the chamber 122 through the extraction grid 126 , and accelerated through the acceleration grid 128 due to a voltage difference between the acceleration grid and the extraction grid to produce an electron beam that flows into the processing chamber 100 .
- Distribution of the plasma ion density and plasma electron density across the chamber 122 affects the uniformity of the electron beam.
- the extraction grid 126 includes a frame 126 - 1 and an array of spaced-apart blocking elements 126 - 2 defining an array of openings 126 - 3 .
- the frame 126 - 1 defines a narrow aperture 126 - 4 whose height H is relatively small (e.g., 2-4 cm) and whose width W (e.g., on the order of the workpiece diameter, or 300 mm or more) is generally parallel to the workpiece support plane of the pedestal 108 , so as to produce a correspondingly thin wide electron beam.
- the distribution of electron density across the width of the beam is liable to exhibit non-uniformities.
- the main plasma source in the electron beam source 120 is a D.C. gas discharge produced by the voltage supply 140
- any other suitable plasma source may be employed instead as the main plasma source.
- the main plasma source of the electron beam source 120 may be a toroidal RF plasma source, a capacitively coupled RE plasma source, or an inductively coupled RF plasma source.
- the main plasma source of the electron beam source 120 is the D.C. gas discharge maintained within he chamber 122 by the D.C. discharge voltage supply 140 .
- This main plasma source is augmented by an array of plasma sources 201 , 202 , 203 and 204 distributed along a direction generally parallel to the workpiece support plane of the pedestal 108 .
- a controller 150 governs the rate at which each plasma source 201 , 202 , 203 and 204 generates plasma ions and electrons, each plasma source, 201 , 202 , 203 , 204 being controlled independently.
- the plasma sources 201 , 202 , 203 and 204 are RF plasma sources employing respective RE power generators 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 , and the controller 150 governs the RE power level of each RE generator 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 separately.
- Each plasma source 201 , 202 , 203 and 204 faces a region 301 , 302 , 303 and 304 of the chamber 122 .
- the output power level of each of the RF generators 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 affects plasma ion density and the plasma electron density in the corresponding region 301 , 302 , 303 and 304 of the chamber 122 .
- the distribution across the electron beam width of electron density reflects the distribution of plasma electron density and plasma ion density along the beam width among the regions 301 , 302 , 303 and 304 within the electron beam source chamber 122 .
- the controller 150 can therefore adjust plasma electron distribution across the width of the electron beam by changing the proportion of RF power output levels of the RF generators 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 .
- Such adjustments may be made in response to measurements of distribution across a test workpiece (processed in the process chamber 100 ) of a process parameter (e.g., etch depth).
- a process parameter e.g., etch depth.
- Non-uniformities in distribution may be ameliorated or corrected by increasing RF power for those regions experiencing lower electron density and/or decreasing RF power for those regions experiencing higher electron density.
- each plasma source 201 - 204 is a toroidal RF plasma source consisting of an external reentrant conduit 210 having a pair of ports 211 , 212 through a back wall 124 - 1 of the chamber 122 , a ring 213 of a magnetically permeable material around the reentrant conduit 210 , a conductive coil 214 around the ring 213 , and an RF generator (e.g., 215 - 1 , 215 - 2 , 215 - 4 ) coupled to the coil 214 through an RF impedance match 216 .
- an RF generator e.g., 215 - 1 , 215 - 2 , 215 - 4
- each plasma source 201 , 202 , 203 and 204 of the electron beam source 120 is a capacitively coupled RF plasma source.
- the conductive housing 124 consists of an upper housing 400 and a lower housing 402 separated by the opening 124 a and by an insulator 405 .
- An insulator 412 overlies the upper housing 400 .
- the plasma sources 201 , 202 , 203 and 204 include separate electrodes 410 - 1 , 410 - 2 , 410 - 2 and 410 - 4 , respectively, overlying the insulator 412 .
- Respective ones of the RF generators 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 are coupled through the individual impedance matches 216 - 1 , 216 - 2 , 214 - 3 and 216 - 4 to respective ones of the electrodes 410 - 1 , 410 - 2 , 415 - 2 and 410 - 4 .
- An insulator 413 underlies the lower housing 402 .
- a common return (RF ground) electrode 411 underlies the insulator 413 .
- a first D.C. voltage supply 420 referenced to ground is connected to the upper and lower housings 400 , 402 .
- the voltage supply 420 is connected through a choke inductor 428 to the upper housing 400 , and through a choke inductor 422 to the lower housing 402 .
- the choke inductors 422 and 423 enable each RF generator 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 to maintain RF voltage differences between the respective electrodes 410 - 1 , 410 - 2 , 410 - 2 and 410 - 4 and the lower housing 402 .
- insulators 412 and 413 as blocking capacitors, the above scheme of connecting both RF and DC voltages to the same points (upper and lower housings 400 and 402 ) resembles a well-known “bias tee” configuration.
- voltage supply 420 may provide a voltage in a high range (e.g., 2-3 kV). This voltage will determine the energy that electrons will gain when passing through the gap between the extraction grid 126 and the grounded acceleration grid 128 .
- a negative terminal of the high-voltage D.C. power supply 420 may he connected through a choke inductor to the extraction grid 126 , instead of the upper and lower housings 400 , 402 .
- a second D.C. voltage supply 430 is connected between the negative terminal of the first D.C. voltage supply 420 and the extraction grid 126 , the positive terminal of the second D.C.
- the second D.C. voltage 430 supply may provide a voltage in a lower range (e.g., 0-300 volts). In one example, this voltage may be small and insufficient to autonomously produce and sustain a D.C. discharge. In this case, DC discharge is not the main plasma source for the electron beam source 120 .
- plasma is produced mostly by the capacitively coupled RF sources, and the DC voltage from the supply 430 is provided primarily to eliminate an electron-repelling sheath at the discharge side of the extraction grid, and thus ensure that electrons can leave the e-beam discharge chamber through the extraction grid.
- each one of the array of plasma source 201 , 202 , 203 and 204 of the electron beam source 120 is an inductively coupled RF plasma source, that includes a coil antenna 510 mounted over a dielectric window 512 formed on the back well 124 - 1 of the chamber 122 , and a respective one of the RF generators 215 - 1 , 215 - 2 , 215 - 3 and 215 - 4 coupled to the of 510 through a respective one of the RF impedance matches 216 .
- the electron beam source 120 has a single plasma source chamber 122 extending across the entire width of the plasma beam, corresponding to the width of the process region 118 of the process chamber 100 .
- the electron beam source 120 is provided with an array of plasma sources 601 , 602 , 603 and 604 constituting separate smaller chambers distributed across the width of the electron beam.
- Each of the plasma sources 601 , 602 , 603 and 604 has a respective chamber 622 - 1 , 522 - 2 , 622 - 3 and 622 - 4 isolated from each other by insulators 623 . D.C.
- discharge voltage supplies 642 - 1 , 642 - 2 , 642 - 3 and 642 - 4 are connected between the walls of the respective chambers 622 - 1 , 622 - 2 , 622 - 3 and 622 - 4 and respective extraction grids 626 - 1 , 626 - 2 , 626 - 3 and 626 - 4 .
- the voltages V 1 , V 2 , V 3 and V 4 are independently controlled by the controller 150 , so that each chamber may be provided with different gas discharge voltages, so as to produce different electron densities.
- the chambers 622 - 1 , 622 - 2 , 622 - 3 and 622 - 4 are open toward the processing chamber 100 through the respective extraction grids 626 - 1 , 626 - 2 , 626 - 3 and 626 - 4 and respective acceleration grids 628 - 1 , 628 - 2 , 628 - 3 and 628 - 4 .
- An accelerating voltage supply 646 is coupled to the extraction grids 626 - 1 , 626 - 2 , 626 - 3 and 626 - 4 through respective variable resistors 630 - 1 , 630 - 2 , 630 - 3 and 630 - 4 , and is referenced to ground.
- variable resistors 630 - 1 , 630 - 2 , 630 - 3 and 630 - 4 are independently controlled by the controller 150 , so that each extraction grid may be provided a different accelerating voltage, so as to accelerate beam electrons to different energies.
- the four plasma sources 601 , 602 , 603 and 604 face respective regions 501 , 502 , 503 , and 504 of the processing chamber 100 and affect electron (and ion) density within those regions.
- the four plasma sources can provide different amounts of plasma to the different regions 501 , 502 , 503 , and 504 .
- the different D.C. discharge voltages provided to the e-beam sources 601 , 602 , 603 and 604 affect plasma ion density and the plasma electron density in the corresponding regions 501 , 502 , 503 and 504 of the processing chamber 100 .
- the distribution of electron density across the combined electron beam width (from all 4 sources) reflects the distribution of plasma electron density and plasma ion density along the beam width among the regions 501 , 502 , 503 and 504 within the processing chamber 100 .
- the controller 150 can therefore adjust plasma density distribution across the width of the electron beam by adjusting the voltages 642 - 1 , 642 - 2 , 642 - 3 and 642 - 4 to provide different D.C. gas discharge voltages to the different chambers 622 - 1 , 622 - 2 , 622 - 3 and 622 - 4 . Such adjustments may be made in response to measurements of distribution across a test workpiece (processed in the process chamber 100 ) of a process parameter (e.g., etch depth).
- a process parameter e.g., etch depth
- the plasma sources 601 , 602 , 603 and 604 may provide different energies of beam electrons in the different regions. This is done by the controller 150 adjusting the variable resistors 630 - 1 , 630 - 2 , 630 - 3 and 630 - 4 . This may be one so as to compensate for non-uniformities in the distribution of plasma density in the chamber 100 . Such non-uniformities may be detected by measuring process results on a test workpiece.
- the electron energy levels of the different plasma sources 601 - 604 are depicted as being controlled by different variable resistors 630 - 1 , 630 - 2 , 630 - 3 , 640 - 4 from a shared accelerating voltage supply 646 , in one modification the same control may be realized by providing separate accelerating voltage supplies (not illustrated) controlled by the controller 150 , rather than separate variable resistors.
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Abstract
Description
- This application claims the benefit of U.S. Provisional Application Ser. No. 61/549,340, filed Oct. 20, 2011 entitled ELECTRON BEAM PLASMA SOURCE WITH ARRAYED PLASMA SOURCES FOR UNIFORM PLASMA GENERATION, by Leonid Dorf, et al.
- A plasma reactor for processing a workpiece can employ an electron beam as a plasma source. Such a plasma reactor can exhibit non-uniform distribution of processing results (e.g., distribution of etch rate across the surface of a workpiece) due to non-uniform distribution of electron density and/or kinetic energy within the electron beam. Such non-uniformities can be distributed along the direction of beam propagation and can also be distributed in a direction transverse to the beam propagation direction.
- A plasma reactor for processing a workpiece, includes a workpiece processing chamber having a processing chamber enclosure comprising a ceiling and a side wall and an electron beam opening in said side wall, a workpiece support pedestal in said processing chamber having a work lace support surface facing said ceiling and defining a workpiece processing region between said workpiece support surface and said ceiling, said electron beam opening facing said workpiece processing region. The plasma reactor further comprises an electron beam source chamber comprising an electron beam source chamber enclosure that is open to said electron beam opening of said workpiece processing chamber, and an array of plasma sources distributed along a portion of said electron beam source chamber enclosure opposite from said electron beam opening, each of said plasma sources comprising a supply of plasma source power and a plasma source power applicator coupled to the supply of plasma source power. A controller governs each supply of plasma source power of each of said plasma sources.
- The array of plasma sources is distributed along direction parallel with a plane of said workpiece support surface.
- The plasma sources affect plasma electron density in respective portions of said electron beam source chamber, said respective portions distributed along a direction parallel with a plane of said workpiece support surface. The plasma reactor of claim 3 wherein said controller governs plasma electron density distribution along said direction.
- So that the manner in which the exemplary embodiments of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be appreciated that certain well known processes are not discussed herein in order to not obscure the invention.
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FIGS. 1A and 1B are top and side views, respectively, of a plasma reactor employing an electron beam to produce a plasma in a workpiece processing chamber, and of the electron beam source including an array of toroidal plasma sources, in accordance with a first embodiment. -
FIG. 1C is an enlarged view of a portion ofFIG. 1B . -
FIG. 1D is a cross-sectional view taken alonglines 1D-1D ofFIG. 1C . -
FIGS. 2A , 2B and 2C are side, top and end views, respectively, of a plasma reactor employing an electron beam to produce a plasma in a workpiece processing chamber, and of the electron beam source including an array of capacitively coupled plasma sources, in accordance with a second embodiment. -
FIGS. 3A and 3B are side and end views, respectively, of a plasma reactor employing an electron beam to produce a plasma in a workpiece processing chamber, and of the electron beam source including an array of inductively coupled plasma sources, in accordance with a third embodiment. -
FIG. 4 is a top view of a plasma reactor employing an electron beam to produce a plasma is a workpiece processing chamber, and of the electron beam source including an array of separate electron beam source chambers, in accordance with a fourth embodiment. - To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
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FIGS. 1A and 1F are top and side views, respectively, of a plasma reactor having an electron beam plasma source employing a configurable array of plasma sources affecting uniformity of an electron beam, in accordance with a first embodiment. The reactor includes aprocess chamber 100 enclosed by acylindrical side wall 102, afloor 104 and aceiling 106. Aworkpiece support pedestal 108 supports aworkpiece 110, such as a semiconductor wafer, the pedestal. 108 being movable in the axial (e.g., vertical) direction. Agas distribution plate 112 is integrated with or mounted on theceiling 106, and receives process gas from aprocess gas supply 114. Avacuum pump 116 evacuates the chamber through thefloor 104. Aprocess region 118 is defined between theworkpiece 110 and thegas distribution plate 112. Within theprocess region 118, the process gas is ionized to produce a plasma for processing of theworkpiece 110. - The plasma is generated in the
process region 118 of theprocess chamber 100 by an electron beam from anelectron beam source 120. Theelectron beam source 120 includes aplasma generation chamber 122 outside of theprocess chamber 100 and having aconductive enclosure 124. Theconductive enclosure 124 has a gas inlet or neck. 125. An electron beamsource gas supply 127 is coupled to thegas inlet 125. Theconductive enclosure 124 has anopening 124 a facing theprocess region 118 through anopening 102 a in thesidewall 102 of theprocess chamber 100 through which the electron beam enters theprocess chamber 100. - The
electron beam source 120 includes anextraction grid 126 between theopening 124 a and theplasma generation chamber 122, and anacceleration grid 128 between theextraction grid 126 and theprocess region 118, best seen in the enlarged view ofFIG. 1C . Theextraction grid 126 and theacceleration grid 128 may be formed as separate conductive meshes, for example. Theextraction grid 126 and theacceleration grid 128 are mounted withinsulators conductive enclosure 124. However, theacceleration grid 128 is in electrical contact with theside wall 102 of thechamber 100. Theopenings acceleration grids processing region 118. The width of the flow path is about the diameter of the workpiece 110 (e.g., 100-500 mm), while the height of the flow path is less than about two inches. - The
electron beam source 120 further includes a pair of electromagnets 134-1 and 134-2 aligned with theelectron beam source 120, and producing a magnetic field parallel to the direction of the electron beam. The electron beam flows across theprocessing region 118 over theworkplece 110, and is absorbed on the opposite side of theprocessing region 118 by abeam dump 136. Thebeam dump 136 is a conductive body having a shape adapted to capture the wide thin electron beam. - A negative terminal of plasma D.C.
discharge voltage supply 140 is coupled to theconductive enclosure 124, whereas a positive terminal of thevoltage supply 140 is connected to theextraction grid 126. In turn, a negative terminal of an electron beamacceleration voltage supply 142 is connected to theextraction grid 126, and positive terminal is connected to thegrounded sidewall 102 of theprocess chamber 100. The electrons extracted from the DC discharge plasma through theextraction grid 126 are accelerated as they travel towards theacceleration grid 128 by the potential difference (typically of the order of a few kV) provided by thevoltage supply 142. In another example, the negative terminal ofvoltage supply 142 may be coupled to theconductive enclosure 124, instead of theextraction grid 126. In this case, thevoltage supply 142 not only performs work to accelerate the electrons, but also to sustain DC discharge. Thevoltage supply 140, in this case, only performs work on a small portion of a discharge current caused by electrons that do not make it through the openings and bombard the extraction grid. A coilcurrent supply 146 is coupled to the electromagnets 134-1 and 134-2. Plasma is generated within thechamber 122 of theelectron beam source 120 by a D.C. gas discharge produced by power from thevoltage supply 140, which provides a voltage typically of the order of a few hundred volts. This D.C. gas discharge is the main plasma source of theelectron beam source 120. Electrons are extracted from the plasma in thechamber 122 through theextraction grid 126, and accelerated through theacceleration grid 128 due to a voltage difference between the acceleration grid and the extraction grid to produce an electron beam that flows into theprocessing chamber 100. Distribution of the plasma ion density and plasma electron density across thechamber 122 affects the uniformity of the electron beam. For example, referring toFIG. 1D , theextraction grid 126 includes a frame 126-1 and an array of spaced-apart blocking elements 126-2 defining an array of openings 126-3. The frame 126-1 defines a narrow aperture 126-4 whose height H is relatively small (e.g., 2-4 cm) and whose width W (e.g., on the order of the workpiece diameter, or 300 mm or more) is generally parallel to the workpiece support plane of thepedestal 108, so as to produce a correspondingly thin wide electron beam. The distribution of electron density across the width of the beam is liable to exhibit non-uniformities. - While the main plasma source in the
electron beam source 120 is a D.C. gas discharge produced by thevoltage supply 140, any other suitable plasma source may be employed instead as the main plasma source. For example, the main plasma source of theelectron beam source 120 may be a toroidal RF plasma source, a capacitively coupled RE plasma source, or an inductively coupled RF plasma source. - In the illustrated embodiment, the main plasma source of the
electron beam source 120 is the D.C. gas discharge maintained within hechamber 122 by the D.C.discharge voltage supply 140. This main plasma source is augmented by an array ofplasma sources pedestal 108. Acontroller 150 governs the rate at which eachplasma source plasma sources controller 150 governs the RE power level of each RE generator 215-1, 215-2, 215-3 and 215-4 separately. Eachplasma source region chamber 122. The output power level of each of the RF generators 215-1, 215-2, 215-3 and 215-4 affects plasma ion density and the plasma electron density in thecorresponding region chamber 122. The distribution across the electron beam width of electron density reflects the distribution of plasma electron density and plasma ion density along the beam width among theregions beam source chamber 122. Thecontroller 150 can therefore adjust plasma electron distribution across the width of the electron beam by changing the proportion of RF power output levels of the RF generators 215-1, 215-2, 215-3 and 215-4. Such adjustments may be made in response to measurements of distribution across a test workpiece (processed in the process chamber 100) of a process parameter (e.g., etch depth). Non-uniformities in distribution may be ameliorated or corrected by increasing RF power for those regions experiencing lower electron density and/or decreasing RF power for those regions experiencing higher electron density. - In the illustrated embodiment, each plasma source 201-204 is a toroidal RF plasma source consisting of an external
reentrant conduit 210 having a pair ofports chamber 122, aring 213 of a magnetically permeable material around thereentrant conduit 210, aconductive coil 214 around thering 213, and an RF generator (e.g., 215-1, 215-2, 215-4) coupled to thecoil 214 through anRF impedance match 216. - In the embodiment of
FIGS. 2A , 2B, 2C, eachplasma source electron beam source 120 is a capacitively coupled RF plasma source. In this embodiment, theconductive housing 124 consists of anupper housing 400 and alower housing 402 separated by the opening 124 a and by aninsulator 405. Aninsulator 412 overlies theupper housing 400. Theplasma sources insulator 412. Respective ones of the RF generators 215-1, 215-2, 215-3 and 215-4 are coupled through the individual impedance matches 216-1, 216-2, 214-3 and 216-4 to respective ones of the electrodes 410-1, 410-2, 415-2 and 410-4. Aninsulator 413 underlies thelower housing 402. A common return (RF ground)electrode 411 underlies theinsulator 413. A firstD.C. voltage supply 420 referenced to ground is connected to the upper andlower housings D.C. voltage supply 420 is connected through a choke inductor 428 to theupper housing 400, and through achoke inductor 422 to thelower housing 402. Thechoke inductors lower housing 402. Consideringinsulators lower housings 400 and 402) resembles a well-known “bias tee” configuration. The firstD.C. voltage supply 420 may provide a voltage in a high range (e.g., 2-3 kV). This voltage will determine the energy that electrons will gain when passing through the gap between theextraction grid 126 and the groundedacceleration grid 128. In another example (not shown inFIG. 2A ), a negative terminal of the high-voltageD.C. power supply 420 may he connected through a choke inductor to theextraction grid 126, instead of the upper andlower housings D.C. voltage supply 430 is connected between the negative terminal of the firstD.C. voltage supply 420 and theextraction grid 126, the positive terminal of the secondD.C. voltage supply 430 being connected through achoke inductor 424 to theextraction grid 126, and the negative, terminals of the first and second D.C. voltage supplies 420, 430 being connected together. Thesecond D.C. voltage 430 supply may provide a voltage in a lower range (e.g., 0-300 volts). In one example, this voltage may be small and insufficient to autonomously produce and sustain a D.C. discharge. In this case, DC discharge is not the main plasma source for theelectron beam source 120. In this example, plasma is produced mostly by the capacitively coupled RF sources, and the DC voltage from thesupply 430 is provided primarily to eliminate an electron-repelling sheath at the discharge side of the extraction grid, and thus ensure that electrons can leave the e-beam discharge chamber through the extraction grid. - In the embodiment of
FIGS. 3A and 3B , each one of the array ofplasma source electron beam source 120 is an inductively coupled RF plasma source, that includes acoil antenna 510 mounted over adielectric window 512 formed on the back well 124-1 of thechamber 122, and a respective one of the RF generators 215-1, 215-2, 215-3 and 215-4 coupled to the of 510 through a respective one of the RF impedance matches 216. - In each of the foregoing embodiments, the
electron beam source 120 has a singleplasma source chamber 122 extending across the entire width of the plasma beam, corresponding to the width of theprocess region 118 of theprocess chamber 100. In the embodiment ofFIG. 4 , theelectron beam source 120 is provided with an array ofplasma sources plasma sources insulators 623. D.C. discharge voltage supplies 642-1, 642-2, 642-3 and 642-4 are connected between the walls of the respective chambers 622-1, 622-2, 622-3 and 622-4 and respective extraction grids 626-1, 626-2, 626-3 and 626-4. The voltages V1, V2, V3 and V4 are independently controlled by thecontroller 150, so that each chamber may be provided with different gas discharge voltages, so as to produce different electron densities. The chambers 622-1, 622-2, 622-3 and 622-4 are open toward theprocessing chamber 100 through the respective extraction grids 626-1, 626-2, 626-3 and 626-4 and respective acceleration grids 628-1, 628-2, 628-3 and 628-4. An acceleratingvoltage supply 646 is coupled to the extraction grids 626-1, 626-2, 626-3 and 626-4 through respective variable resistors 630-1, 630-2, 630-3 and 630-4, and is referenced to ground. The variable resistors 630-1, 630-2, 630-3 and 630-4 are independently controlled by thecontroller 150, so that each extraction grid may be provided a different accelerating voltage, so as to accelerate beam electrons to different energies. - The four
plasma sources respective regions processing chamber 100 and affect electron (and ion) density within those regions. The four plasma sources can provide different amounts of plasma to thedifferent regions e-beam sources regions processing chamber 100. The distribution of electron density across the combined electron beam width (from all 4 sources) reflects the distribution of plasma electron density and plasma ion density along the beam width among theregions processing chamber 100. Thecontroller 150 can therefore adjust plasma density distribution across the width of the electron beam by adjusting the voltages 642-1, 642-2, 642-3 and 642-4 to provide different D.C. gas discharge voltages to the different chambers 622-1, 622-2, 622-3 and 622-4. Such adjustments may be made in response to measurements of distribution across a test workpiece (processed in the process chamber 100) of a process parameter (e.g., etch depth). - In addition to providing different densities of beam electrons in the
different regions plasma sources controller 150 adjusting the variable resistors 630-1, 630-2, 630-3 and 630-4. This may be one so as to compensate for non-uniformities in the distribution of plasma density in thechamber 100. Such non-uniformities may be detected by measuring process results on a test workpiece. While the electron energy levels of the different plasma sources 601-604 are depicted as being controlled by different variable resistors 630-1, 630-2, 630-3, 640-4 from a shared acceleratingvoltage supply 646, in one modification the same control may be realized by providing separate accelerating voltage supplies (not illustrated) controlled by thecontroller 150, rather than separate variable resistors. - While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (25)
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US13/595,201 US9129777B2 (en) | 2011-10-20 | 2012-08-27 | Electron beam plasma source with arrayed plasma sources for uniform plasma generation |
PCT/US2012/060031 WO2013059094A1 (en) | 2011-10-20 | 2012-10-12 | Electron beam plasma source with arrayed plasma sources for uniform plasma generation |
TW101138447A TW201318026A (en) | 2011-10-20 | 2012-10-18 | Electron beam plasma source with arrayed plasma sources for uniform plasma generation |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140265855A1 (en) * | 2013-03-12 | 2014-09-18 | Applied Materials, Inc. | Electron beam plasma source with segmented suppression electrode for uniform plasma generation |
US20170250370A1 (en) * | 2016-02-26 | 2017-08-31 | Applied Materials, Inc. | Methods for integration of organic and inorganic materials for oled encapsulating structures |
CN107195519A (en) * | 2017-07-07 | 2017-09-22 | 桂林电子科技大学 | A kind of Windows of beam of high energy charged particles from vacuum to air |
US20170338080A1 (en) * | 2016-05-19 | 2017-11-23 | Plasmotica, LLC | Apparatus and method for programmable spatially selective nanoscale surface functionalization |
US10388528B2 (en) | 2013-03-15 | 2019-08-20 | Tokyo Electron Limited | Non-ambipolar electric pressure plasma uniformity control |
US20200027688A1 (en) * | 2018-07-19 | 2020-01-23 | Tokyo Electron Limited | Substrate processing apparatus |
WO2021055095A1 (en) * | 2019-09-17 | 2021-03-25 | Tokyo Electron Limited | Plasma processing apparatuses including multiple electron sources |
US11101113B2 (en) * | 2015-03-17 | 2021-08-24 | Applied Materials, Inc. | Ion-ion plasma atomic layer etch process |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9799491B2 (en) * | 2015-10-29 | 2017-10-24 | Applied Materials, Inc. | Low electron temperature etch chamber with independent control over plasma density, radical composition and ion energy for atomic precision etching |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6211622B1 (en) * | 1998-11-10 | 2001-04-03 | Kawasaki Jukogyo Kabushiki Kaisha | Plasma processing equipment |
WO2011024174A1 (en) * | 2009-08-27 | 2011-03-03 | Mosaic Crystals Ltd. | Penetrating plasma generating apparatus for high vacuum chambers |
Family Cites Families (37)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3755073A (en) | 1971-06-21 | 1973-08-28 | Atomic Energy Commission | Hybrid laser plasma target - neutral beam injection fusion system |
US5003178A (en) | 1988-11-14 | 1991-03-26 | Electron Vision Corporation | Large-area uniform electron source |
US20020004309A1 (en) | 1990-07-31 | 2002-01-10 | Kenneth S. Collins | Processes used in an inductively coupled plasma reactor |
JPH04326725A (en) | 1991-04-26 | 1992-11-16 | Tokyo Electron Ltd | Plasma apparatus |
KR100271244B1 (en) | 1993-09-07 | 2000-11-01 | 히가시 데쓰로 | Eletron beam excited plasma system |
JPH08222553A (en) | 1995-02-16 | 1996-08-30 | Tokyo Electron Ltd | Processor and processing |
GB2326971B (en) | 1997-07-03 | 2001-12-12 | Applied Materials Inc | Electron flood apparatus for neutralising charge build up on a substrate during ion implantation |
US5874807A (en) | 1997-08-27 | 1999-02-23 | The United States Of America As Represented By The Secretary Of The Navy | Large area plasma processing system (LAPPS) |
US5903106A (en) | 1997-11-17 | 1999-05-11 | Wj Semiconductor Equipment Group, Inc. | Plasma generating apparatus having an electrostatic shield |
JP2970654B1 (en) | 1998-05-22 | 1999-11-02 | 日新電機株式会社 | Thin film forming equipment |
JP2991192B1 (en) | 1998-07-23 | 1999-12-20 | 日本電気株式会社 | Plasma processing method and plasma processing apparatus |
JP2001085414A (en) | 1999-09-17 | 2001-03-30 | Matsushita Electric Ind Co Ltd | Device and method for plasma treatment |
US6407399B1 (en) | 1999-09-30 | 2002-06-18 | Electron Vision Corporation | Uniformity correction for large area electron source |
US6356026B1 (en) | 1999-11-24 | 2002-03-12 | Texas Instruments Incorporated | Ion implant source with multiple indirectly-heated electron sources |
US6452338B1 (en) | 1999-12-13 | 2002-09-17 | Semequip, Inc. | Electron beam ion source with integral low-temperature vaporizer |
US20020078893A1 (en) | 2000-05-18 | 2002-06-27 | Applied Materials , Inc. | Plasma enhanced chemical processing reactor and method |
US6291940B1 (en) | 2000-06-09 | 2001-09-18 | Applied Materials, Inc. | Blanker array for a multipixel electron source |
US6804327B2 (en) | 2001-04-03 | 2004-10-12 | Lambda Physik Ag | Method and apparatus for generating high output power gas discharge based source of extreme ultraviolet radiation and/or soft x-rays |
US20030090190A1 (en) | 2001-06-14 | 2003-05-15 | Hyperion Catalysis International, Inc. | Field emission devices using modified carbon nanotubes |
US6803582B2 (en) | 2002-11-29 | 2004-10-12 | Oregon Health & Science University | One dimensional beam blanker array |
US20060105182A1 (en) | 2004-11-16 | 2006-05-18 | Applied Materials, Inc. | Erosion resistant textured chamber surface |
KR20050008065A (en) | 2003-07-14 | 2005-01-21 | 삼성전자주식회사 | High density plasma source |
DE10336273A1 (en) | 2003-08-07 | 2005-03-10 | Fraunhofer Ges Forschung | Device for generating EUV and soft X-radiation |
US7470329B2 (en) | 2003-08-12 | 2008-12-30 | University Of Maryland | Method and system for nanoscale plasma processing of objects |
EP1891657A2 (en) | 2005-06-03 | 2008-02-27 | Axcelis Technologies, Inc. | Beam stop and beam tuning methods |
US20070278417A1 (en) | 2005-07-01 | 2007-12-06 | Horsky Thomas N | Ion implantation ion source, system and method |
JP2007051996A (en) | 2005-08-19 | 2007-03-01 | Ngk Insulators Ltd | Electron beam irradiation device |
KR20070041220A (en) | 2005-10-14 | 2007-04-18 | 세메스 주식회사 | Plasma treatment apparatus |
US7498592B2 (en) | 2006-06-28 | 2009-03-03 | Wisconsin Alumni Research Foundation | Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams |
KR101358779B1 (en) | 2007-07-19 | 2014-02-04 | 주식회사 뉴파워 프라즈마 | Plasma reactor having multi-core plasma generation plate |
EP2073243B1 (en) | 2007-12-21 | 2018-10-03 | Applied Materials, Inc. | Linear electron source, evaporator using linear electron source, and applications of electron sources |
US9997325B2 (en) | 2008-07-17 | 2018-06-12 | Verity Instruments, Inc. | Electron beam exciter for use in chemical analysis in processing systems |
US20110199027A1 (en) | 2008-10-16 | 2011-08-18 | Yong Hwan Kim | Electron beam generator having adjustable beam width |
US9269546B2 (en) | 2010-10-22 | 2016-02-23 | Applied Materials, Inc. | Plasma reactor with electron beam plasma source having a uniform magnetic field |
US20120258607A1 (en) | 2011-04-11 | 2012-10-11 | Lam Research Corporation | E-Beam Enhanced Decoupled Source for Semiconductor Processing |
US9111728B2 (en) | 2011-04-11 | 2015-08-18 | Lam Research Corporation | E-beam enhanced decoupled source for semiconductor processing |
US9177756B2 (en) | 2011-04-11 | 2015-11-03 | Lam Research Corporation | E-beam enhanced decoupled source for semiconductor processing |
-
2012
- 2012-08-27 US US13/595,201 patent/US9129777B2/en active Active
- 2012-10-12 WO PCT/US2012/060031 patent/WO2013059094A1/en active Application Filing
- 2012-10-18 TW TW101138447A patent/TW201318026A/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6211622B1 (en) * | 1998-11-10 | 2001-04-03 | Kawasaki Jukogyo Kabushiki Kaisha | Plasma processing equipment |
WO2011024174A1 (en) * | 2009-08-27 | 2011-03-03 | Mosaic Crystals Ltd. | Penetrating plasma generating apparatus for high vacuum chambers |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9443700B2 (en) * | 2013-03-12 | 2016-09-13 | Applied Materials, Inc. | Electron beam plasma source with segmented suppression electrode for uniform plasma generation |
US20140265855A1 (en) * | 2013-03-12 | 2014-09-18 | Applied Materials, Inc. | Electron beam plasma source with segmented suppression electrode for uniform plasma generation |
US10388528B2 (en) | 2013-03-15 | 2019-08-20 | Tokyo Electron Limited | Non-ambipolar electric pressure plasma uniformity control |
US11101113B2 (en) * | 2015-03-17 | 2021-08-24 | Applied Materials, Inc. | Ion-ion plasma atomic layer etch process |
US20170250370A1 (en) * | 2016-02-26 | 2017-08-31 | Applied Materials, Inc. | Methods for integration of organic and inorganic materials for oled encapsulating structures |
US10832895B2 (en) | 2016-05-19 | 2020-11-10 | Plasmotica, LLC | Stand alone microfluidic analytical chip device |
US10497541B2 (en) | 2016-05-19 | 2019-12-03 | Nedal Saleh | Apparatus and method for programmable spatially selective nanoscale surface functionalization |
US20170338080A1 (en) * | 2016-05-19 | 2017-11-23 | Plasmotica, LLC | Apparatus and method for programmable spatially selective nanoscale surface functionalization |
CN107195519A (en) * | 2017-07-07 | 2017-09-22 | 桂林电子科技大学 | A kind of Windows of beam of high energy charged particles from vacuum to air |
US20200027688A1 (en) * | 2018-07-19 | 2020-01-23 | Tokyo Electron Limited | Substrate processing apparatus |
US10665416B2 (en) * | 2018-07-19 | 2020-05-26 | Tokyo Electron Limited | Substrate processing apparatus |
WO2021055095A1 (en) * | 2019-09-17 | 2021-03-25 | Tokyo Electron Limited | Plasma processing apparatuses including multiple electron sources |
US11043362B2 (en) | 2019-09-17 | 2021-06-22 | Tokyo Electron Limited | Plasma processing apparatuses including multiple electron sources |
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